SAN FRANCISCO -- Arrest rates have dropped for all racial groups in California over the last decade, but African Americans are still much more likely than whites to be arrested on felony charges, according to a report released Friday.

In 2015, blacks were 10 times as likely as whites to be arrested on robbery charges and three to five times as likely to be arrested on charges of burglary, theft or assault, according to the report from the state attorney general's office. For felonies involving narcotics, black men were six times as likely as white men to be arrested, and black women were 2.9 times as likely as white women, the report said.

The disparity was even larger for charges of prostitution, in which black women were 20 times as likely to be arrested as white women.

The differences were much less for Latinos, who were about twice as likely as non-Latino whites to be arrested for robbery and were arrested at about the same rate as whites for narcotics. The report also noted that the racial gap was much larger a decade ago, when African Americans in California were about 17 times as likely as whites to be arrested on narcotics charges.

Still, Attorney General Kamala Harris said in a statement, the data show ``pervasive inequalities in our criminal justice system. ... We must continue the national dialogue about criminal justice reform and promote the American idea that we are all equal under the law.''

The report noted the effect of Proposition 47, the 2014 initiative that reclassified drug possession and theft crimes under $950 as misdemeanors instead of felonies.

Felony arrests in California dropped by 29 percent in 2015, the report said, while misdemeanor arrests increased by 11 percent.

But arrests have also declined over a longer period, the report said: by 17.5 percent, or an average of 32,500 a year, since 2008.

The racial gap is disturbing but not surprising, said Rory Little, a law professor at the University of California at Hastings in San Francisco and a former federal prosecutor.

``The exact numbers change, but no matter what people do, there seems to be a persistent racial disparity,'' Little said.

In part, he said, it reflects differences in income, as police tend to patrol more in poorer neighborhoods, which also are more likely to be communities of color. Another reason, he said, is ``unconscious bias,'' which police share with the rest of society.

``If you (the officer) see a poorly dressed person walking down the street looking in car windows, you might follow the black person more than the white person,'' Little said. If asked for an explanation, the officer would probably say, ``He just looked suspicious to me.''